The present invention relates to a cathodic sputtering chamber for applying material to the surface of a semiconductor wafer located in the chamber by means of cathodic sputtering a target, located on a target mount, of the material to be applied or a component thereof, the semiconductor wafer being located on a wafer mount by which it is movable in the chamber between a charging position for its application to the wafer mount and a sputtering position in which it is located at a predefined distance away from and opposite to the target.
One method of applying coatings to the semiconductor wafers in the fabrication of integrated circuits is cathodic sputtering. In this method, the semiconductor wafer to be coated is brought into a chamber so that it is located at a predefined distance away from and opposite to the target composed of the material, or a component thereof, as is to be deposited as a coating on the semiconductor wafer. In this chamber an argon plasma is generated at low pressure. In this arrangement the positively charged argon ions are accelerated in the plasma to the target having a negative potential. Due to the impact of the argon ions, material is sputtered from the target which is then deposited on the surface of the semiconductor wafer located opposite the target, together with any other material as introduced necessary into the sputtering space. One problem encountered in the application of the cathodic sputtering method is that the material sputtered from the target surface deposits not only on the surface of the semiconductor wafer to be coated, but on all inner walls of the chamber in which the plasma is generated. To prevent this unwanted deposition on the inner walls of the chamber, a shielding device is installed in the chamber which surrounds the space between the target and the semiconductor wafer like a cylinder and features an annular radial section extending towards the semiconductor wafer, the diameter of which is smaller than that of the target. To secure the semiconductor wafer to a wafer mount a supporting device is used which surrounds the semiconductor wafer annularly in holding it against the wafer mount by means of a protruding lip. Both the shielding device as well as the supporting device need to be removed from the chamber at regular intervals for cleaning, since the target material depositing thereon tends to fragmentate after several deposition cycles, resulting in particles being liberated which could be deposited on the surface of the semiconductor wafer and ruin parts of the integrated circuits formed thereon. If cleaning is not done often enough, the reject rate of the semiconductor circuits increases sigificantly. However, frequent cleaning sigificantly reduces the thruput of semiconductor wafers to be coated, since having to open the chamber, remove and clean the shielding device and supporting device, subsequently reinstalling these devices and re-evacuating the chamber, all take up a lot of time. The problem of the target material fragmenting and being deposited unwantedly on the shielding device and supporting device occurs more particularly in the case of brittle materials such as TiN or TiW normally requiring to be deposited on the surface of the semiconductor wafers in the fabrication of integrated semiconductor circuits.